Foldable display devices have been developed in recent years. A particular demand for larger screens leads to development of a display device including foldable two cases each provided with a display.
Patent Literatures 1 and 2 describe a foldable mobile terminal including a first case having a first display, and a second case having a second display. The first and second cases are connected to each other at a hinge part so as to be foldable at the hinge part to be opened and closed.
The display device described in Patent Literatures 1 and 2 includes the displays provided respectively in the two cases. The two displays form a boundary therebetween which cannot be disregarded. If a single flexible display is applied to a foldable structure to eliminate such a boundary, the display receives a large load at a folded portion.
Patent Literature 3 discloses a display device including first to third cases and a single flexible display extending from the second case to the third case. The first case according to Patent Literature 3 is provided for an electronic circuit. The first and second cases are connected to each other via a hinge part so as to be foldable at the hinge part. The second and third cases are made of a plastic material, each include opposite side walls having a bellows sectional shape, and are connected to each other via an expandable hinge part having a hollow interior. The display device is folded by interposing the first case between the second and third cases in a state where the first and second cases are stacked. This configuration prevents the display provided across the second and third cases from being folded at an acute angle, and secures long durability of the display.
Patent Literature 4 discloses a display device including two cases connected to be foldable at a hinge unit, a flexible display unit such as an organic EL display panel, and an elastic sheet member disposed on the rear surface of the display unit. The elastic sheet member is fixed to a first one of the cases so as to be slidable with respect to a second one of the cases. This configuration releases stress applied to a folded mobile phone and protects the display unit.